1. Field of the Invention
The invention relates to valves and relates particularly to float valves especially suited to maintaining the level of water in a tank, such as a stock watering tank, at or below a desired level.
2. Description of the State of the Art
Float valves are known and they are used in a wide variety of applications to keep the volume or quantity of a liquid in a container below a desired value or within a desired range of values. Float valves operate automatically to prevent the level of liquid in a tank from exceeding a maximum desired level by controlling the flow of liquid into the tank. A float valve has a valve that closes when the liquid level reaches an upper limit. As the liquid level falls, the valve opens and the flow of liquid into the tank is resumed and continues until the liquid level reaches the upper limit. The valve is opened and closed mechanically by the float and the position of the float determines when the valve will be open and when the valve will be closed and when the valve will be in an intermediate position. The position of the float depends upon the liquid level in the tank. When the liquid level reaches the upper limit, the float moves up and closes the valve. When the level of liquid in the tank falls, the float moves down and the valve opens. The position of the float depends, at least in part, upon the buoyancy of the float relative to the liquid.
U.S. Pat. No. 4,274,365 discloses an automatic watering device comprising a float valve. A float controlled valve assembly is described in U.S. Pat. No. 4,064,895. Myriad float valves are distributed through Tractor Supply Co. including those originating through Little Giant and Newell Rubbermaid. Manta-Ray, Inc. in West Unity Ohio manufactures and distributes many types of float valves.
Known livestock watering tank float valves operate so that the valve closes when the water level in the tank reaches a desired maximum level. When the valve is closed and the water level in the tank is being drawn down, as when livestock are drinking from the tank, the tank is draining and the level of the float will go down. If the float level continues to go down, eventually a point is reached where the valve will open, ever so slightly, and liquid will begin to flow through the valve into the tank. So long as the tank is draining, the level of the float will continue to go down. The float will stop going down when the tank stops draining or when the float reaches the limit of its downward travel. As the float valve goes down and the valve opens further, in some cases it reaches a full open position and the rate of flow of water through the valve into the tank will reach a maximum rate. Throughout this specification, the rate of flow of water through the valve into the tank will be referred to as the filling rate. The draining rate refers to the rate at which water is being drawn out of the tank, without taking into account the filling rate. Thus, when the filling rate is greater than the draining rate, the tank is filling and the water level is rising. When the draining rate is greater than the filling rate, the tank is draining and the water level is falling. When the two rates are equal, the tank is neither filling nor draining and the water level remains constant. Known float valves are described further, below.
If the tank is draining, the level of the float will go down. When the level of the float gets low enough, the valve will reach a full open position and the filling rate will be at a maximum. Even with the valve fully opened and the filling rate at the maximum, if the draining rate is greater than the filling rate, the tank will be draining. When the valve is open at all, and the tank is filling, the valve will be moving into the closed position and the filling rate will be getting lower and lower. A condition known as seeping occurs when the filling rate is very low. Seeping is a condition where the filling rate is so slow that the water may be said to be seeping into the tank. In a case where a pump supplies water to the valve for filling the tank, the seeping condition can lead to problems for the pump.
Pumps are set to maintain a line pressure between an upper setting and a lower setting. When the line pressure falls to the lower setting, the pump activates and runs until the line pressure reaches the upper setting and the pump shuts off. When the filling rate is very low, the pump will run only a short time during each cycle because the upper pressure setting is reached very quickly. In this situation, the pump will have to cycle very many times before the valve closes because the liquid level in the tank is rising so very slowly—water is only seeping into the tank. Each time that an electric pump starts, its power consumption spikes. Thus, an electric pump in a system that requires the pump to cycle very frequently, per gallon pumped, will use more energy than a pump in a system in which the pump is cycled less frequently, per gallon pumped. In addition, an electric pump can only start and stop so many times before it wears out. Thus, an electric pump in a system that requires the pump to cycle very frequently, per gallon pumped, will wear out faster than a pump in a system in which the pump is cycled less frequently, per gallon pumped.
It is an object of the invention to provide a durable and reliable float valve for maintaining a liquid level in a container at or below a high level mark.
It is a further object of the invention to provide such a valve that is especially suited for use with a stock water tank.
It is still another object of the invention to provide such a valve which can close, at least under some conditions, without seeping.
It is a further object of the invention to provide a float valve that will contribute to an associated pump using less energy.
It is a still further object of the invention to provide a float valve that will contribute to a longer life for an associated pump.
It is yet another object of this invention to provide such a valve which is especially suited for easy manufacturing and assembly.
These and other objects and advantages of the present invention shall be apparent from the following detailed description with reference, therein, to the several drawing figures.